1. Field of the Invention
The present invention relates to an attachment system for adjusting the clearance between an impeller and a suction housing of a standard impeller pump.
2. Background of the Prior Art
In a typical impeller pump, such as the Model 3196 series of pumps produced by Gould Pumps, Inc., of Seneca Falls N.Y., the bearing housing and the bearing frame are two separate items attached to one another. A first series of generally evenly spaced apart bolts, typically three in number and referred to as attaching bolts, pass through the bearing housing and are threadably received within the bearing frame. A second series of generally spaced apart (from each other and from the first series of bolts) bolts, also typically three in number and referred to as held bolts, pass threadably through the bearing housing and abut the bearing frame. The clearance achieved between the impeller and the suction housing (the impeller clearance) is in the order of a fraction of an inch with the precise clearance being pump size and model specific. The first series of bolts and the second series of bolts cooperatively work to achieve the desired clearance. Tightening of the first series of bolts draws the impeller closer to the suction housing while tightening the second series of bolts moves the impeller further from the suction housing. Applying the proper torque to each series of bolts will produce the appropriate push and pull forces on the pump elements (shaft, bearings, impeller, and bearing housing) such that the desired clearance between the impeller and the suction housing is achieved and the pump operates with maximum efficiency.
The factory recommended torque for these bolts for the Model 3196 pumps is 23 foot-pounds lubricated and 33 foot-pounds dry. If the bolts are torqued to factory specifications, the shaft acts as a lever and loads the floating bearing and the held bearing. This removes the running clearance between the rotating balls of the bearing and the inner and outer races of the bearing greatly reducing the running life of the bearing. This also causes the pump to work hard and thus operate less efficiently.
Therefore, there is a need in the art for a mechanism that will provide for the appropriate adjustment in order to achieve the appropriate clearance between the impeller and the suction housing without preloading the bearings. The mechanism must be simple in design and must be quick and easy to use. The device must not rely on specialized tools such as torque wrenches in order to achieve the desired result.